Rail holddown combination



Feb. 10, 1970 F. K. HALL 3,494,556

RAIL HOLDDOWN COMBINATION Filed Feb. 25, 1968 r 2 Sheets-Sheet l JET //Vl E/V7'0/?. FRANK KENNETH HALL Feb. 10, F K. HALL RAIL HOLDDOWN COMBINATION 2 Sheets-Sheet 2 Filed Feb. 25, 1968 m w I: a I y w 2 a 4 I 6 2 p H W 5 m 4 M v 7 \A 3 w w Q INVENTOR. RANK KEN/V5777 HALL Um'ted States Patent M 3,494,556 RAIL HOLDDOWN COMBINATION Frank Kenneth Hall, Findlay, Ohio, assignor to The D. S. Brown Company, North Baltimore, Ohio, a corporation of Ohio Filed Feb. 23, 1968, Ser. No. 707,491 Int. Cl. E01b 21/04, 29/24, 9/38 U.S. Cl. 238349 15 Claims ABSTRACT OF THE DISCLOSURE Rail holddown system embodying holddown assembly with resiliently biased holddown members pressing against upper face of base flange of railroad rail; resilient bias preferably is compressed elastomer body positioned between holddown member and cross leg of inverted U-member.

BACKGROUND OF THE INVENTION The present invention concerns holddown systems particularly adapted to securely position a railroad rail on a support member or underlying structure. The invention particularly concerns the holddown systems adapted for use with concrete ties, concrete beds, metal superstructures, and like support structures. It further pertains to other uses wherein one member is to be held in position relative to another member and may be used in lieu of bolt connections, welded connections, etc.

Railroad rails traditionally have been mounted on wooden cross ties spaced at close intervals by the driving of railroad spikes into the ties with the head portion of the spike overlapping the base flange of the rail. This has been true of below ground and on ground rail systems and above ground, or elevated, rail systems. With the fairly recent advent of improvements in the structural strength of concrete, rail systems embodying concrete ties or concrete beds have awakened the interest of railroad designers. Concrete beds or ties require considerable less maintenance and have a longer useful life than do the traditional wooden ties.

The adaptation of rail systems to the use of concrete ties and concrete road beds, however, also requires a departure from the traditional concept of holding the rail on the ties, i.e., by spikes being driven into the wooden ties. Holddown systems for rails on concrete ties and/ or concrete road beds or metal superstructures have been developed in recent years. Known holddown systems embody heavy metal structures. Some utilize metal components in torsion stress as the force-exerting members. A specific object of the present invention concerns improvements in rail holddown systems wherein the traditional, wooden ties concept is abandoned in favor of prestressed concrete ties, metal superstructures and/or concrete road beds in below ground, on ground or elevated rail systems.

BRIEF SUMMARY OF THE INVENTION Briefly, the invention concerns holding systems in general, i.e., systems for holding one member relative to another comprising a first member, a second member contiguous thereto to be held in fixed position relative to said first member, and means for transmitting thrust between said members including a compressively deformed bias member, preferably a solid elastomer body having opposite substantially parallel faces exerting an outward elastic recovery thrust against substantially parallel faces with lines of thrust forces in said com- 3,494,556 Patented Feb. 10, 1970 pressively deformed member being essentially at right angles to said faces. An exemplary use thereof comprises rail holddown systems wherein the railroad rails are secured by a series of holddown devices materially different from and considerably improved over the traditional railroad spike. A base member of such device may be fixedly secured relative to a concrete bed or tie or to other structural systems supporting the rail, such as metal superstructures in the case of elevated rail systems. This base member may be a base plate bolted or otherwise attached to the road bed, concrete tie or superstructure. The system further embodies a holddown member comprising a holddown or pressure plate pressed downwardly against the upper face of the base flange. The pressure exerted thereby is of a relatively high magnitude, i.e., in the order of at least several hundred psi. and a total force of at least two thousand pounds. This pressure is provided by a resilient bias member, preferably elastomer pressure body, positioned between a fixed inverted U-member and the holddown member. The elastomer body is distorted compressively from its normal, unstressed state whereby the elastic recovery thrust forces resulting from the compressive distortion exerts a pressure thrust force of relatively high magnitude, sufficient to secure the rail tightly on ties or other rail support members.

The elastomer pressure member is inserted in the hold down system on the construction site. As is well known, it is diflicult to insert an elastomer member in a highly compressed state. To facilitate such insertion, the elastomer member may be compressively distorted or flattened, whereafter its temperature is lowered sufliciently to immobilize or freeze the member in the compressed or flattened state when the compression force is removed. It is maintained at this temperature until it is inserted on the job in the holddown system. Upon thawing or Warming, the elastomer body regains its elastic recovery property and recovers toward its normal shape, which is the shape of the elastomer member before compressive distortion and low temperature immobilization thereof. The holddown system is dimensioned so that the inserted elastomer member cannot recover fully its original or normal shape, whereby the elastomer member is in a partially compressed state when it exerts its thrust force against the holddown member. Thereby, there exists in effect the elastomer member in a partially compressed state. Through the utilization of the elastic recovery force of said member in attempting to return it to its original or normal state, it functions as the pressure exerting body in the holddown system.

The elastomer member may also be compressed between opposing, preferably substantially parallel faces of a holddown system or the like by other means. For example, the elastomer member may be inserted in an uncompressed state, and one or more shims may be driven between the body and the contiguous face of the holddown member to compress the elastomer member. A1- ternatively, the holddown device may be made in separate parts and assembled on the job site in a manner whereby the elastomer member is compressed upon assembly. In rail holddown systems, the holddown units may be mounted on the rail without the elastomer member, which is inserted later.

systems of the type disclosed in my pending application, Serial No. 704,052, filed on February 8, 1968. The improvements herein reside in holddown structures embodying a base plate extending transversely beneath the railroad rail. The base plate has provided thereon a holddown unit comprising an inverted U-member having a substantially flat cross leg extending transversely across and above the base (substantially parallel with the rail). The inverted U-member is adjacent the base flange of the railroad rail and there are preferably two, opposed, holddown units on each base plate on opposite sides of the base flange. The holddown member has an inner portion resting against the upper face of the base flange of the rail and extends from said base flange outwardly through the inverted U-member. A resilient bias member, preferably a solid elastomer body, under compressive distortion, is provided between the aforesaid cross leg and the holddown member. The elastic recovery of the resilient bias member presses the flange-contacting portion of the holddown member downwardly against the upper face of the base flange to give a secure mounting of the railroad rail on the aforesaid base plate, which is in turn securely mounted by bolts or the like on concrete railroad ties, concrete rail beds, metal superstructures, or the like.

DESCRIPTION OF THE DRAWINGS Several preferred forms of the invention are illustrated in the drawings wherein:

FIGURE 1 is an end elevation of an embodiment of a rail holddown system with the railroad rail shown in cross section and the underlying concrete tie shown in fragment;

FIGURE 2 is a top plan view thereof with the rail and tie shown in fragment;

FIGURE 3 is a side elevation thereof with the rail and tie shown in fragment;

FIGURE 4 is an end elevation of the second embodiment of a rail holddown system with the rail shown in cross section;

FIGURE 5 is a top plan View thereof with the rail shown in fragment; and

FIGURE 6 is a side elevation thereof with the rail shown in fragment.

DESCRIPTION OF PREFERRED EMBODIMENTS The embodiment of FIGURES 13 constitutes a rail holddown assembly wherein the assembly is attached, e.g., by bolts, to a rail supporting structure, which may be a series of railroad ties, an elevated, ground or below ground level railroad bed, or a series of cross structures such as steel structural members of an elevated monorail or dual rail system. The ties or railroad bed may be of any suitable material, but generally will be concrete. The rail 10 has the usual base flange 11, the upper surface 12 of which generally slopes outwardly but may be at right angles to the vertical axis of the rail if desired In the illustrated embodiment the rail holddown system is mounted on the upper face of a concrete tie 13. Each concrete cross tie has secured to its upped face a rail holddown unit 15. The unit 15 comprises a base plate 16 mounted on the tie by bolts 17 and nuts 17a tightened against bearing or washer plates 18 having a stepped lower segment 19 seated in the rectangular apertures 14 in the outer portions of the base plate 16. The bolts 17 are fixedly embedded in the tie 13.

The upper surface of the base plate 16 has a pair of transverse V-grooves 20 which serve as the receiving grooves for the mounting of each metal loop-strap 21 on the upper face of the base plate 16. The base leg 22 of each loop-strap is welded or otherwise rigidly secured to base plate 16 in each transverse groove 20. The two side legs 23 and the top, cross leg 24 of loop-straps 21 provide an inverted U-strap extending outwardly diagonally upwardly (optionally vertically) from the base plate 16.

The base plate has a pair of additional transverse grooves 26 in its upper surface outwardly of the grooves 20. These grooves receive a respective side leg 27 of the inverted, U-shaped pressure or holddown member 28 for proper positioning of the latter in the assembly. The other side leg 29 of each pressure or holddown member 28 rests on the upper surface 12 of the base flange 11. The cross leg 30 of the pressure holddown member 28 extends through the loop-strap 21. The downward pressure of side legs 29 on the upper surface 12 of base flange 11 is provided by inserting between the upper surface of cross leg 30 and lower surface of top, cross leg 24 of strap 21 a resilient bias member 31 under compressive distortion in the assembly. The resilient bias member in the illustrated embodiment is a compressively distorted, solid elastomer body, e.g., a block or slab of solid elastomer. If desired, an elastomer pad 32 may be inserted under rail flange 11.

The embodiment of FIGURES 4-6 comprises a holddown unit 35 having a flat base plate 36. A pair of U- straps 37 comprising side legs 38 and cross leg 39 are welded along the lower edges of said legs 38 to the outer longitudinal edges of the base plate 36 on opposite sides of the rail 10. A notched gauge bar 46 with legs 38 in its notches functions as a spacer between a longitudinal edge of base flange 11 and the fixed member 37 to hold rail 10 against lateral sliding under lateral thrust such as exerted by railway wheels against the outer rail in a curved section of track.

There is a cross bar 41 extending transversely of the base plate 36 contiguous to the outer edges of each U- strap 37. The function of the cross bars 41 is to provide a seat or retainer against which the outer edge 43 of the substantially flat cross plate 42 rests for proper positioning thereof, and also to prevent the latter from working outwardly.

The under face 44 of the cross plate 42 is angularly disposed so that it rests substantially flatly on the sloping upper surface 12 of the base flange 11. The under face 44 is pressed tightly against the upper surface 12 by a compressively distorted, resilient bias member 45, which comprises in the illustrated embodiment a compressively distorted, solid elastomer body orv block.

The preferred pressure exerting members comprise an elastomer block or body which is compressively distorted in the assembly of the rail with the holddown devices. Prior to inserting them, these blocks or bodies are distorted by compression into a flattened form, with a dimension slightly less than the spaces between cross legs 30 or 39 and holddown members 28 and 42. They are inserted in the distorted or compressed shape and thereafter allowed to recover via the elastic forces of the elastomer block or body toward its normal state, i.e., the shape it would assume without any compressive forces exerted thereon. In this elastic recovery, the elastomer bodies press against these holddown members and thus exert a downward thrust thereon. This force is in turn transmitted against the upper face 12 of the base flange 11 to hold the rail securely in position.

The opposing faces of the cross legs 29 and 39 and respective holddown members 28 and 42 are preferably substantially parallel, planar faces for achieving maximum effect of the thrust forces of the resilient bias members 31 and 45. The latter, in turn, are generally rectangular parallelepipeds in the relaxed (undistorted) state having a height or thickness considerably greater than the distance between said opposing faces.

As aforesaid, it normally would be difficult to insert the compressively distorted, elastomer bodies between said faces. To facilitate such insertion, it is preferred that the elastomer bodies be compressively distorted in a flattened shape and frozen or immobilized in this state. They are held at the freezing or low temperature immobilization until inserted. As the elastomer bodies warm their resilient properties are restored and they seek to resume their shape prior to compressive distortion and freezing. In

so doing, they become wedged between said faces and thus exert a downward thrust on the holddown members.

The terms freezing and thawing above, are nontechnical descriptions. In practice, the elastomer bodies are formulated so that the elastomer composition will rigidify, through loss of elastic properties, at relatively low temperatures, i.e., in the order of -40 F. and below. The elastomers also should have good resistance to atmospheric deterioration in the presence of sunlight, atmospheric oxygen, and ozone, and should retain their elastic properties also at relatively high temperatures on the order of 100 to 120 F. The elastomer compositions useful for this purpose may be formulated from elastomers which crystallize at relatively low temperatures with the loss of elastic properties upon crystallization. Exemplary thereof are low crystallization neoprene elastomers. However, elastomers which are usually considered to be noncrystalline elastomers, e.g., natural rubber and most synthetic rubbers, can be immobilized or rigidified in the compressively distorted state at low temperatures in the order of 0 F. to 100 F. or even lower. The invention herein contemplates use of any natural or synthetic rubber composition wherein such low temperature immobilization can be attained. The selection of a particular elastomer composition will depend in part on the climate of the locale where the installation is made. In northern parts of the temperate zone, a low temperature immobilization of 30 F. or below is recommended. In the arctic zone, a low temperature immobilization of 60 F. or below is recommended, whereas in southern parts of the temperate zone and in the tropical zone 0 F. or below would be suitable. In each instance, the lower temperature immobilization is selected so that it will not be reached and preferably not even closely approached under the coldest climate conditions of the particular locale.

Thus, in its broader concepts the invention herein provides a system for holding one member relative to another by a compressively distorted, resilient bias member, preferably a solid elastomer body or block. The system embodies a first member and a second member to be held in fixed position relative to the first member. The system embodies substantially parallel, opposed faces against which the compressively distorted elastomer body is positioned with its opposite faces pressing against said opposed faces to give an elastic recovery thrust force urging said faces apart along lines of thrust force at right angles to said faces. This combination utilizes the elastic recovery forces in the compressed elastomer body more effectively than would be the case if the elastomer body were subject to twisting. In the latter case, the torque elastic recovery forces in the twisted elastomer adopt a sine curve-like configuration. Such recovery forces are considerably less effective in terms of amount of elastic recovery thrust forces per unit of distortion or deformation of the elastomer body as compared against the thrust force orientation achieved by this invention.

It is thought that the invention and its numerous attendant advantages will be fully understood from the foregoing description, and it is obvious that numerous changes may be made in the form, construction and arrangement of the several parts without departing from the spirit or scope of the invention, or sacrificing any of its attendant advantages, the forms herein disclosed being preferred embodiments for the purpose of illustrating the invention.

The invention is hereby claimed as follows:

1. In a rail holddown system embodying a railroad rail having a base flange extending along the base thereof and supported on an underlying structure, the improvement comprising a rail holddown unit embodying a base plate, an inverted U-member on said plate adjacent said flange and having a cross leg extending transversely across and above said base plate, a holddown member extending through said U-member with an inner portion thereof resting against the upper face of said flange, and a body of solid elastomer under compressive distortion between said cross leg and said holddown member and pressing said inner portion against said upper face.

2. The improvements as claimed in claim 1 wherein said bias member is a block of solid elastomer.

3. The improvement as claimed in claim 1 wherein said holddown member comprises a cross plate extending through said U-member, said body of solid elastomer being compressively distorted between said cross leg and cross plate and pressing against said cross plate downwardly, and a leg depending from the inner edge of said cross plate and constituting said inner portion.

4. The improvement as claimed in claim 3 wherein said bias member is a block of solid elastomer.

5. The improvement as claimed in claim 3, an additional leg depending from the outer portion of said cross plate, and seat-forming means on the upper surface of said base plate forming a seat for said additional leg.

-6. The improvement as claimed in claim 5 wherein said seat-forming means is a transverse groove in the upper surface of said base plate.

7. The improvement as claimed in claim 1 wherein said holddown member comprises a substantially fiat, cross plate extending through said U-member, said body of solid elastomer being compressively distorted between said cross leg and cross plate and pressing said cross plate downwardly, and the inner portion of the under face of said cross plate lying substantially flatly against said flange.

8. The improvement as claimed in claim 7 wherein said bias member is a block of solid elastomer.

9. The improvement as claimed in claim 7, abutment means extending transversely across the upper surface of said base plate adjacent the outer edge of said cross plate and forming a stop against outward displacement of said cross plate.

10. The improvement as claimed in claim 9 wherein said abutment means comprises a bar on said upper surface.

11. The improvement wherein said base plate extends transversely beneath said rail and said rail holddown unit comprises two, opposing assemblies of an inverted U-member, a holddown member and a body of solid elastomer, respectively, as defined in claim 1, said assemblies being mounted on said base plate respectively contiguous to respective longitudinal, opposite edges of said base flange of said rail.

12. The improvement wherein said base plate extends transversely beneath said rail and said rail holddown unit comprises two, opposing assemblies of an inverted U-member, a holddown member and a body of solid elastomer, respectively, as defined in claim 3, said assemblies being mounted on said base plate respectively contiguous to respective longitudinal, opposite edges of said base flange of said rail.

13. The improvement wherein said base plate extends transversely beneath said rail and said rail holddown unit comprises two, opposing assemblies of an inverted U- member, a holddown member and a body of solid elastomer, respectively, as defined in claim 5, said assemblies being mounted on said base plate respectively contiguous to respective longitudinal, opposite edges of said base flange of said rail.

14. The improvement wherein said base plate extends transversely beneath said rail and said rail holddown unit comprises two, opposing assemblies of an inverted U-member, a holddown member and a body of solid elastomer, respectively, as defined in claim 7, said assemblies being mounted on said base plate respectively contiguous to respective longitudinal, opposite edges of said base flange of said rail.

15. The improvement wherein said base plate extends transversely beneath said rail and said rail holddown unit comprises two, opposing assemblies of an inverted U-member, a holddown member and a body of solid 7 elastomer, respectively, as defined in claim 9, said as semblies being mounted on said base plate respectively contiguous to respective longitudinal, opposite edges of said base flange of said rail.

References Cited UNITED STATES PATENTS 8 2,535,337 12/1950 Wertz 238349 3,338,520 8/1967 Dinger 238-349 3,383,043 5/1968 Tew 238283 ARTHUR L. LA POINT, Primary Examiner R. A. BERTSCH, Assistant Examiner US. Cl. X.R. 238283 

